Process for the sterilization of liquids



y 29- C. A. HARTUNG I 1,714,366

PROCESS FOR THE STERILIZATION 0F LIQUIDS Filed May 8, 1926 f/VVEMTOf-PCarl A. Hal-fang E) f 420/ Mg? Patented May 21, 1929.

UNITED STATES PATENT OFFICE.

CARL ADOLF HAR'IUNG, OF BERLIN, GERMANY.

Application filed May 8, 1926, Serial No.

When sterilizing goods, such as some kinds of liquid food stuff forexample, which are sensitive to heat it is diflicult to prevent thetaste of the food being disagreeably affected. Various apparatus havebeen devised with the object of preventing this drawback, and remedy hasbeen sought by circulating the liquid quickly past heating surfaces ofspeinfluence of undue heating. However, all these deviceshave provedinsuflicientas it was not possible to avoid local overheating of thegoods to be sterilized. One of the 1mdesirable results is the occurrenceof albuminous deposits upon the heating surfaces forming a sticky, slimycoating which materially retards the heating process, so that localoverheating is, instead of being avoided, incurred all the more. Theundesirable result of such local overheating is, apart from thedaifectedtaste, a noxious smell ,of burnt foo The new process according to theinvention avoids these disadvantages and results in a sterilized productwhich is free from noxious tastes and odors. According to the inventionthe process mainly consists in circulating the liquid to be sterilizedfrom a container past heating devices by means of which it is heatedindirectly by another liquid on the heat exchanging principle; the saidheating liquid being maintained at only a few degrees above thetemperature of the liquid under treatment. Thus the increase in thetemperature of the heating medium in the heating device takes place inexactl the same measure in which the heated liqui increases itstemperature. The difference between the temperature of the heatingmedium and that of the liquid to be sterilized is ke t approximatelyconstant at all places, so t at any in- 'jurious effects of overheatingare successfully avoided, whilst the time required to properly heat theproduct to complete sterilization is reduced to the shortest possible.

The new process will now be described with reference to the accompanyingdrawing which is a diagrammatic illustration of a device suited to carrout the said process; the drawing being only an example of such device,for various other arrangements may be devised to carry out the newprocess.

In this drawing the eontainerfor the liquid to be sterilized is denotedby a; it is in communication with the heater b, workin on the exchangeprinciple, by means of a pipe 0 107,781, and in Germany March 25, 1926.

through which the liquid from the container enters the heater, and apipe (Z through which it returns. The heater b contains a closed pipesystem which is shown in the form of a coil in broken lines. Circulationof the liquid through the system takes place automatically by the heatedparts of the liquid con- .stantly rising to the surface. cial shape inorder to avoid the disagreeable The closed tube system of .the heater 6is encircled by another tube system through which the heating mediumflows which, in this case, is assumed to be water and which iscirculated through the system by means of a small centrifugal pump e viathe pipes f and 9. These said pipes contain a steam jet h by means ofwhich the circulating heating medium may be heated by opening the steamvalve 11. A reservoir is is provided to compensate for both loss andexpansion of the heating medium through the pipe I.

' Thermometers m and a are provided in the tubes 0 and g respectively,and it is the duty of the attendant to so regulate the steam supply bymeans of the mixing device h, i as to alwaysapproximately maintain thatdifference-of temperature between the liquid under treatment and theheating medium, which has been found to give the most satisfactory re-'sults.

Instead of the hand regulation referred to it is evident, that thetemperature may be regulated .by some known or convenient automatictemperature regulating device, by causing the heating medium or theliquid under treatment to be influenced by two heat regulators which areacted upon by the temperature of the liquids in the pipes c and d. As afurtheralternative one regulator may be so influenced by thetemperatures in these two tubesas to always maintain a constant"difference of temperature in the system.

What I claim is The process of sterilizing liqpids, comprisingcirculating the liquid to 0 treated, recurrently from a reservoir, incountercurrent relation to a heated medium, until the desiredtemperature of the body of liquid to he treated is obtained, andregulating the temperature of the heating medium so as to maintain itconstant, at an elevation of but a few degrees above the temperature ofthe liquid to be treated with which it is at that time in heat exchangimrelation.

In testimony whereof I ailix my signature.

CARL ADOLF HARTUNG.

